It is generally known that objects made of foamed polyester resins are stronger both in tensile and elongation strength than nonfoamed polyesters. Foamed polyesters are also more capable of absorbing shock. As a result, there is an active interest in the development of safe, inexpensive methods for preparing foamed polyesters.
Although objects are commercially available which are prepared by known methods of preparing foamed polyesters, the methods that have been employed are not without disadvantage. Some of the previously known methods require the use of expensive mixing apparatus; others require relatively expensive ingredients and still others may require heating the mold and/or resin mixture. Therefore, a need still exists for a safe, inexpensive, simple method of preparing foamed polyesters.